We propose to develop the use of plasmon-controlled fluorescence (PCF) and to apply this technology to the detection of cardiac markers. The effective use of PCF for sensing will depend on an understanding of the interactions of fluorophores with metallic nanostructures. These studies will provide the basis for using plasmon-controlled fluorescence (PCF) in medical diagnostics and biotechnology. This proposal evolved from our studies of the effects of random size metallic particles (silver island films, SIFs) and planar surfaces on nearby fluorophores. These studies showed that fluorophore-metal interactions result in modification of excitation and emission by enhancement of local incident fields and coupling of excited state energy into plasmons, which then radiate to the far field for detection. Our Specific Aims are: Specific Aim 1: Nanofabrication of metallic nanostructures, including regular nanoparticle arrays, nanohole arrays and concentric nanorings. Specific Aim 2. Determine the effects of these structures on nearby fluorophores, including intensities, lifetimes, photostability and directionality of the emission. We will also determine the effect of distance from the surface on these spectral properties. Specific Aim 3. Correlate the near-field properties of these structures with their effects on fluorescence. Near-field properties of the structures will be determined experimentally using NSOM, which will be used to measure and image the evanescent field and light propagating away from the metal surfaces. These results will be compared with finite-difference time-domain (FDTD) calculations for the same structure. Specific Aim 4. Use the metallic nanostructures for assays of the cardiac markers myoglobin, creatinine kinase (CK-MB), cardiac troponin l(cTnl) and B-type natriuretic peptide (BNB). For these analytes we will perform testing for specificity, sensitivity and reproducibility. The clinically relevant concentration of myogloblin are relatively high and this marker will be used for initial assay development. Cardiac troponin I and BMP are present at lower concentrations and their detection will drive development of nanostructures for high sensitivity detection.